Congressional work on President Trump’s $1 trillion infrastructure package may slip to next year, a Republican chairman said Thursday.

Lawmakers are facing a pile of other priorities, while the White House has yet to unveil formal legislative text for its massive rebuilding proposal.

“They’re supposedly going to submit some sort of plan in the fall, so we’ll see,” Sen. John Thune, chairman of the Commerce, Science and Transportation Committee, told reporters. “We’re sort of waiting on the administration to tell us what it is exactly they want to do.”

“That ... would be an interesting debate and discussion, which might spill into next year,” he added.

The administration has been eager to show progress on Trump’s ambitious effort to upgrade U.S. roads, bridges and airports. The White House launched a week-long “infrastructure week” initiative earlier this month to ramp up support for the rebuilding proposal and offer new clues about the plan.

But before lawmakers can move on to the infrastructure package, they still need to tackle healthcare and tax reform – two major Trump priorities that are shaping up to be a heavy lift. Meanwhile, Congress will also be consumed with several "must-pass" bills over the next few months, including measures related to aviation, the debt ceiling and government spending.

“I look at the calendar and realize how hard it’s going to be to transact major legislation that requires a good amount of floor time,” Thune said.